The present invention relates, in general, to semiconductor components and, more particularly, to metallization systems in semiconductor components. Semiconductor components include one or more semiconductor devices manufactured from a semiconductor substrate. Typically, metal interconnects are formed over the semiconductor substrate to electrically connect semiconductor devices to each other or to electrical contacts for transmission of electrical signals to other devices. FIG. 1 is a cross-sectional view of a prior art semiconductor component 10 formed from a silicon substrate 12. Although not shown, semiconductor devices are formed from silicon substrate 12. An aluminum layer 14 is formed on silicon substrate 12 and a dielectric passivation layer 16 is formed over a portion of aluminum layer 14 and over silicon substrate 12. A seed metal layer 18 is formed on the portion of aluminum layer 14 that is unprotected by dielectric passivation layer 16 and over a portion of dielectric passivation layer 16. A copper interconnect 20 having a top surface 26 and side surfaces 28 is formed on seed metal layer 18 using an electroplating technique. An electroless nickel gold (Ni/Au) protective structure 22 is formed on the exposed surfaces of copper interconnect 20, where protective structure 22 comprises a layer of nickel 23 formed on copper interconnect 20 and a layer of gold 25 formed on nickel layer 23. Aluminum layer 14, seed metal layer 18, and copper interconnect 20 form a metallization system 24. A drawback with this approach is that when seed metal layer 18 is etched away, it may be overetched or undercut forming an undercut region 19. Acids or other contaminants may be trapped in undercut region 19 which cause corrosion and degrade the reliability of semiconductor component 10. Another drawback is that the manufacturing flow includes two separate and expensive plating processes.
FIG. 2 is a cross-sectional view of another prior art semiconductor component 50. Semiconductor component 50 is similar to semiconductor component 10 except that protective structure 22 is absent from top surface 26 and side surfaces 28 and an electroplated metal structure 52 is formed on top surface 26 of copper interconnect 20 but is absent from side surfaces 28. Metal structure 52 may be an electroplated metal layer 53 in contact with copper interconnect 20 and an electroplated layer metal layer 55 in contact with nickel layer 53. Metal layer 53 may be nickel and metal layer 55 may be palladium or metal layer 53 may be nickel and metal layer 55 may be gold or the like. A layer of gold 54 is formed on nickel palladium layer 52. A disadvantage of semiconductor component 50 is that side surfaces 28 are unprotected and susceptible to corrosion and electromigration.
Accordingly, it would be advantageous to have a method for protecting metallization systems and a metallization system that protects against electro-migration and corrosion. It would be of further advantage for the method and structure to be cost efficient to implement.